DESCRIPTION: (Applicant's Abstract) Nuclear sclerosis, and its clinically important manifestation as nuclear cataract, is a common age-related ocular problem. In Beaver Dam, Wisconsin, nuclear cataract was the most common cataract type to precede lens extraction While older age and female gender are associated with increased risk, other factors have been found and still other, hypothesized to also be associated with risk, some positively and others negatively. Many current epidemiologic studies of nuclear sclerosis use slit lamp photographs to document severity and compare these with photographic standards to assign severity levels. The resultant grades, while in general ordered as to severity, are variable regarding repeat masked gradings by the same and by different graders. Thus, effects of risk or protective factor, which may be small to moderate, may be missed. We have developed a semi-automated scheme for measuring nuclear density, a reflection of nuclear sclerosis, from previously collected photographs. The method reflects current manual grading schemes in ordering severity, but is highly reproducible. We propose to apply these methods to slit lamp photographs taken three times over a ten-year interval in the large cohort participating in the Beaver Dam Eye Study. This will permit quantitation of nuclear sclerosis in a more reliable manner and on a finer scale than with current manual grading. We propose to examine relationships between previously hypothesized risk and protective factors for prevalent severity of nuclear sclerosis at baseline and for its progression, and to estimate the association of nuclear density with measures of visual function. The advantages of developing and testing these procedures in the Beaver Dam Eye Study are that (1) the data are from a free-living, unselected population in which the spectrum nuclear sclerosis is likely to represent that in other similar communities and (2) the photographs are in hand and thus the project is economical. The approach described will be important in clinical trials that are ongoing, others that have been completed, and still others that are planned by the National Eye Institute and other groups in which finding small to moderate affects will be enhanced by more reliable measures of disease.